1. Field of Invention
The present invention relates to an electrooptical panel that allows wirings for supplying signals to a plurality of scanning lines to be routed at a high density, a method for driving the electrooptical panel, and electronic equipment employing the electrooptical panel.
2. Description of Related Art
Currently, an active-matrix liquid-crystal panel can include an element substrate having switching elements which are respectively connected to pixel electrodes arranged in a matrix, and a plurality of data lines, to which the ends of the switching elements are respectively connected. The active-matrix liquid-crystal panel can further include a counter substrate having the scanning lines, a color filter and the like, and a liquid crystal interposed between the two substrates.
A two-terminal non-linear element such as a thin-film diode (TFD) may be used as the switching element in this arrangement. When a voltage above a predetermined threshold voltage of the switching element is supplied between the data line and the scanning line, the switching element is turned on, storing a predetermined charge in a liquid-crystal layer. Subsequent to the storage of charge, a voltage below the predetermined threshold voltage is applied to the switching element, thereby turning off the switching element, when the resistance of the liquid-crystal layer is high enough, the charge is maintained in the liquid-crystal layer. Accordingly, when the quantity of stored charge is controlled by driving the switching element, the liquid crystal may change the orientation state thereof, thereby presenting predetermined information. Since the period of time during which the charge is stored in the liquid-crystal layer in each pixel with a signal voltage applied to turn on the switching element is part of the time, selecting the scanning lines in a time-division manner permits a multiplex driving method in which each of the scanning lines and the data lines are shared with a plurality of pixels.
A plurality of wirings can be arranged to supply each scanning line with the signal voltage in this type of liquid-crystal panel. The wiring is arranged for each scanning line, and as the number of scanning lines becomes large, the spacing between the wirings needs to be narrowed. A low-resistance material is preferably used for the wirings from the standpoint of power saving. To this end, a metal such as chromium is typically used as a wiring material.
However, if a metal is used for a wiring material, the wiring material is subject to degradation due to electrolytic corrosion. The deterioration of the wirings due to electrolytic corrosion becomes serious as the spacing between the wirings is narrow, and as a line-to-line voltage between wirings is large. For this reason, the spacing between the wirings is determined so that reliability of the panel is not deviated from within a permissible range as a result of the deterioration of the wirings due to electrolytic corrosion.
On the other hand, as the spacing between the wirings widens, the area of the wirings occupying in the liquid-crystal panel becomes large, leading to a bulky liquid-crystal panel and a cost increase.